1. Field of the Invention
The invention relates to the field of radio frequency receivers utilized within wireless communication systems, and more particularly to synchronization of symbol timing for such radio frequency receivers.
2. Description of the Related Art
Wireless communication systems typically utilize a radio frequency transmitter for wirelessly transmitting data, and a radio frequency receiver for receiving the transmitted data. However, the radio frequency transmitter and the radio frequency receiver typically operate under the control of different clocks. As such, although the clocks of the two devices are designed to operate under the same frequency, there is a likelihood of a clock rate difference between the radio frequency transmitter and the radio frequency receiver. This clock rate difference can cause the receiver to see incoming data at a rate which is different than that expected, thus leading to improper acknowledgment and processing of the data.
As such, the radio frequency receiver cannot start randomly at any time. Rather, the radio frequency receiver needs to know a certain time index to detect the transmitted data. This timing index can be provided by using a symbol timing.
In conventional approaches, synchronization of symbol timing typically relies on signal correlations within a received signal. Such conventional approaches typically calculate a symbol timing as follows:
                              C          n                =                              ∑                          i              =              0                                      N              -              1                                ⁢                                          ⁢                                    y              ⁡                              (                                  n                  -                  i                                )                                      ⁢            y            *                          (                              n                -                i                -                L                            )                                                          (                  Equation          ⁢                                          ⁢          1                )            where Cn represents a symbol timing candidate, y(n) represents the received signal, L represents the symbol duration between two neighboring identical symbols, and N denotes the correlation block size. The received signal y(n) is a complex value having real and imaginary (quadrature) components, and y*(n) is the complex conjugate. Symbol timing {circumflex over (n)} can be found at the position where Cn reaches its peak value, substantially as follows:
                              n          ^                =                              max            n                    ⁢                      (                                                        C                n                                                    )                                              (                  Equation          ⁢                                          ⁢          2                )            
Although the conventional approaches are capable of symbol timing synchronization, they are not without problems. For example, since the above equations are seen to include complex multiplications and additions, implementation costs, surface requirements and power consumption can be high. Accordingly, a symbol timing method with lower complexity and simpler structure, but comparable performance, is desired.